They get fired inside so its not a projectile
Pre detonation spray , it seems to go off once it hits the volatility mix? That blue is a strange color. It's incredibly consistent here. It makes me think there's two liquids being sprayed. That is like, copper blue. Maybe it's just a trick of the light. Might just be butune. That sounds like a blue gas.
I thought I saw a bit of flame so I palatized it and sure enough there is. That sort of weak ass fire screams methanol but methanol should be liquid... so maybe hydrogen? Not in this economy. But it doesn't stay lit. because here we see what looks like a taser discharge? Butane I guess. That's pretty cheap.
Yeah taser confirmed. I also can recognize the sound of a taser for the same reason I can recognize the sound of compressed air leaving a cylinder.

2 combustion methods. One of them looks like a twisted wire arker, the other looks like a spark plug.

ONSGLM is the brand of a butane lighter gun series. 46 volts is a voltage sufficient enough to engage a solenoid. But I feel like anyone using a butane lighter for this wouldn't be using a solenoid.

Final clue comes from that orange liquid on the bottom. If you follow the line up it enters the chamber. But that's a very low pressure line so it's not going to be anything explosive. It's probably just powered by expansion.
Now I feel like we have enough to conclude that the earliest models of these are compressed butane lighters that build up in a cylinder, shot out, and then ignited with a secondary mechanism like a taser or spark plug. There was one demonstration of a multishot one with an obvious pilot light and I didn't feel like the pressure was too impressive. Maybe there's a pressure escape valve he's using. That would explain the build up and the way everyone seems to hold it. But that wouldn't explain why he's so comfortable firing it indoors so maybe it is a solenoid.
The later generations are a bit of a mystery. Obvious there's a butane component but we see this mystery fluid entering the chamber and I don't like how it looks like the burn actually has entered into it. I think all the other cylinders here hold wiring for the electrical except the steel ones. I notice another handle directly inline with the orange container, making me thing it's probably the second trigger. So the final design looks something like this.